MAYBE

Problem:
 a(a(b(b(x)))) -> b(b(b(a(a(a(x))))))
 a(c(x)) -> c(a(x))
 c(b(x)) -> b(c(x))
 dup(A'(a(b(b(x))))) -> collapse(A'(a(x)),A'(a(x)))
 collapse(x,y) -> dup(x)
 collapse(x,y) -> dup(y)

Proof:
 Open